Where cores come from

A core is code with full access to your server and data. The source matters.

Official sources

The Millida catalog installs cores from these sources — you don't need to download anything manually.

Why third-party builds are dangerous

“Optimized” and “improved” cores from forums come with:

• miners and backdoors;
• built-in telemetry;
• disabled security checks;
• modifications that break plugin compatibility.

You can't spot any of this from the description — How to check a server for a backdoor.

Your own core

If you have a legitimate reason to use your own .jar — verify the checksum and keep the source under control — Your own .jar.

A red flag

A core that asks you to disable anti-cheat, only works with a specific Java version, or demands that you “don't update” is a reason to drop it.